1. Field of the Invention
The present invention relates to an X-ray computerized tomography apparatus. The present invention relates, more particularly, to a technique for achieving a prompt and real-time display of a display image of a desired arbitrary target object within a subject by easily detecting a position of the object at a high speed, and for improving the efficiency of the operation in a navigation of an operation or the like, for example.
2. Description of the Background
In the application field of an X-ray computerized tomography apparatus, there has been known so-called a CT fluoroscopy or a real-time CT (hereinafter referred as a CT fluoroscope) utilizing a real-time reconstructing method for reconstructing and displaying acquired projection data in real time. By utilizing this CT fluoroscopy technique, it is possible to carry out a navigation of an operation including a biopsy for collecting an organization of a target object such as a tumor from a subject, and an insertion of a catheter
In this case, a photographing of a tomographic image of the subject is carried out first, by using an X-ray computerized tomography apparatus. Then, an insertion object such as a catheter or a puncture needle is inserted into the subject, and this insertion object is reached to a target object like a tumor existing inside the subject, while confirming the tomographic image displayed on the screen.
As a conventional X-ray computerized tomography apparatus for carrying out an operation support, there has been known an operation supporting system disclosed in U.S. patent application Ser. No. 5,848,126, xe2x80x9cRadiation Computed Tomography Apparatusxe2x80x9d. According to this operation supporting system, an image reconstructing of a subject is carried out after scanning the subject, to generate image data consisting of data of a plurality of slices. Then, a position of an insertion object is detected from this image data, and a tomographic image including a slice having a tip of the insertion object is displayed on the screen.
The above-described conventional art, however, has the following problems.
FIG. 1 shows a procedure of reaching a target object inside a subject by a biopsy or the like according to the conventional art. At first, an operator inserts a puncture needle into the subject while watching a display image (step S101). In this case, according to the image display based on the conventional X-ray computerized tomography apparatus, as the insertion object is inserted into the subject, the tip of the insertion object is deviated from the image of a slice displayed, so that the tip (probe tip) of the insertion object is lost from the view field. When the insertion object such as puncture needle tip is deviated from the image (step S102Y), a doctor (or the operator) moves a gantry or a couch to change a slice to be displayed on the screen while observing the image (step S103). Until the image of the puncture needle tip is confirmed (step S104Y), the move of the gantry or the couch in step S103 has to be repeated, and then the puncture needle reaches a target position (step S105Y), these processes have to be repeated. In other words, the operator always needs to move the gantry or the couch in search of the tip of the insertion object, which work has required a considerably large word load.
Further, according to the above-described operation supporting system, it has been necessary to provide an insertion object supporting member having a position detecting function (sensor function), for detecting the tip of the insertion object. The provision of the insertion object supporting member for the insertion object has made it difficult to carry out a free operation of the insertion object.
Furthermore, according to the above-described operation supporting system, after the subject has been scanned, image reconstructing is carried out for the data acquired by the scanning, to thereby prepare image data. The insertion object is detected from this reconstructed image data. However, the series of the Image reconstructing and the image data preparation processing takes long hours. Therefore, it has not been possible to detect and display the insertion object in real time.
On the other hand, the photographing of a target organ in the subject has required the following complex operation.
FIG. 2 shows a procedure for photographing a target organ inside a subject.
At first, the operator lays a patient on the couch (step S601), and photographs a whole scanogram of this patient (the subject) (step S602). Next, the operator determines a scan position for photographing the target organ on the image (step S603) while observing the photographed scanogram image. The operator operates to start the scanning (step S604), and obtains a tomographic image of the target organ.
The series of the above procedure takes long hours, and the operation required therefor has been complex
The present invention has been made to overcome the above-described problems of the conventional art. It is an object of the present invention to provide an X-ray computerized tomography apparatus capable of real-time reconstructing and displaying an image of a slice in which a target object such as an insertion object inside a subject exists so as to accurately and promptly carry out a navigation of an operation.
It is another object of the present invention to provide an x-ray computerized tomography apparatus capable of decreasing an unnecessary exposure of a subject to X-rays, by real-time acquiring transmission data of only a slice in which a target object such as an insertion object inside the subject exists.
Further, it is still another object of the present invention to provide an X-ray computerized tomography apparatus capable of improving the operation efficiency of the photographing of a target organ inside a subject.
In order to achieve the above objects, a first feature of the present invention resides in directly detecting a position of an object inside a subject from transmission data acquired (i.e., projection data). Based on the information of the detected position, it is possible to determine a range in which an image should be reconstructed, a range in which an image should be displayed (visualized), or a range in which a subject should be scanned, and to carry out a prompt processing in a necessary range.
Further, a second feature of the present invention resides in displaying arbitrary data among acquired transmission data, together with a display image of a reconstructed image. By displaying this transmission data, It is possible to easily understand in real time the progress state of an insertion object three-dimensionally.
According to one aspect of the present invention, there is provided, as shown in FIG. 3, an X-ray computerized tomography apparatus, comprising: an X-ray detection unit 23 for detecting transmission X-rays from a plurality of directions Irradiated from an X-ray beam generation source 21 and transmitted through a subject; a data acquisition unit 27 for acquiring transmission data according to the transmission X-rays detected by the X-ray detection unit; an object position detection unit 31 for detecting a position of an object inside the subject, according to a part of the transmission data acquired by the data acquisition unit; a reconstructing range determining unit 46 for determining a slice to be image-reconstructed, according to the position detected by the object position detection unit; and an image reconstruction unit 45 for reconstructing a tomographic image of a slice in which the object exists, according to the transmission data acquired by the data acquisition unit, the transmission data being acquired in the slice determined by the reconstruction range determining unit.
The object position detection unit 31 may include a transmission data extraction unit 33 for extracting transmission data at a predetermined tube position of the X-ray beam generation source, for each slice, from the transmission data acquired by the data acquisition unit, whereby to detect a position of the target object according to the extracted transmission data.
As shown in FIG. 14, the X-ray computerized tomography apparatus may further comprise a tube position determining unit 39 for determining the predetermined tube position of the X-ray beam generation source, based on the transmission data of a plurality of slices from a plurality of directions acquired by the data acquisition unit, and for sending data showing a determined tube position to the transmission data extraction unit.
Further, according to another aspect of the present invention, there is provided, as shown in FIG. 3, an X-ray computerized tomography apparatus, comprising: an X-ray detection unit 23 for detecting transmission X-rays from a plurality of directions irradiated from an X-ray beam generation source 21 and transmitted through a subject; a data acquisition unit 27 for acquiring transmission data according to the transmission X-rays detected by the X-ray detection unit; an object position detection unit 31 for detecting a position of an object inside the subject, according to a part of the transmission data acquired by the data acquisition unit: a visualizing-range detection unit 48 for determining a slice in which an image should be visualized, according to the position detected by the object position detection unit; an image reconstruction unit 45 for reconstructing a tomographic image, according to the transmission data acquired by the data acquisition unit; and a display unit 47 for visualizing the tomographic image of a slice determined by the visualizing-range detection unit.
Further, according to still another aspect of the present invention, there is provided, as shown in FIG. 24, an X-ray computerized tomography apparatus, comprising: an X-ray detection unit 23 for detecting transmission X-rays from a plurality of directions irradiated from an X-ray beam generation source 21 and transmitted through a subject; a data acquisition unit 27 for acquiring transmission data according to the transmission X-rays detected by the X-ray detection unit; an object position detection unit 31 for detecting a position of an object inside the subject, according to a part of the transmission data acquired by the data acquisition unit: and a scanning range determining unit 49 for determining a range in which the subject is to be scanned, according to the position detected by the object position detection unit.
The scanning range determining unit may alternatively be structured as a collimator controlling unit 59a shown in FIG. 19 or a collimator controlling unit 59b shown in FIG. 20, for controlling an X-ray Irradiation quantity by a shielding plate.
Further, according to still another aspect of the present invention, there is provided, as shown in FIG. 21, an X-ray computerized tomography apparatus, comprising: an X-ray detection unit 23 having detecting elements laid out in a plurality of rows in a slice direction, for detecting transmission X-rays from a plurality of directions irradiated from an X-ray beam generation source 21 and transmitted through a subject: a data acquisition unit 27 for collecting transmission data according to the transmission X-rays detected by the X-ray detection unit; an image reconstruction unit 45 for reconstructing a tomographic image of a slice in which an object inside the subject exists, according to the transmission data acquired by the data acquisition unit; and a display unit 47 for displaying an image of transmission data at a predetermined tube position of the X-ray beam generation source from among the transmission data acquired by the data acquisition unit, together with a tomographic image reconstructed by the image reconstruction nit.
Further, according to still another aspect of the present Invention, there is provided, as shown in FIG. 3, an X-ray computerized tomography apparatus, comprising: an X-ray detection unit 23 having detecting elements laid out in a plurality of rows in a slice direction, for detecting transmission X-rays for a plurality of slices from a plurality of directions irradiated from an X-ray beam generation source 21 and transmitted through a subject; a data acquisition unit 27 for acquiring transmission data according to the transmission X-rays detected by the X-ray detection unit: an object position detection unit 31 for detecting a position of an object inside the subject, according to transmission data at a predetermined tube position of the X-ray beam generation source out of the transmission data for a plurality of slices acquired by the data acquisition unit; a visualizing-range detection unit 48 for determining a slice in which an image should be visualized, according to the position detected by the object position detection unit; an image reconstruction unit 45 for reconstructing a tomographic image, according to the transmission data acquired by the data acquisition unit; and a display unit 47 for visualizing the tomographic image of a slice determined by the visualizing-range detection unit 48.